[vtk-developers] vtkProcessObject::GetNumberOfRequiredInputs()

[David Gobbi]

Hi Andrew,

Nope, we're not making a drag-and-drop interface, in fact we're making
a plugin interface but drag-and-drop seemed like a better way to explain
the issue of needing to know the number of required inputs ahead of time,
"filters as components" is a very good description.

The plugin interface I'm developing uses Python, which allows me to easily
probe a filter at runtime to see what methods are available and even to
provide a description (in English) of the filter to the user.  The
NumberOfRequiredInputs was the only important piece of info I couldn't
probe.  XML is a good idea too, I'm sure that the guys at Kitware have
already done some work in that direction.

 - David


On Wed, 10 Dec 2003, Andrew Dolgert wrote:

> Are you making a drag-and-drop visual interface more automatic than
> Paraview?  Having more than just the number of inputs would let you
> treat filters as components, with guarantees that, given the right
> input, they will work.  Subclasses of vtkDataSet ensure the topology and
> geometry are correct for a filter, but filters also have other
> requirements on the dataset, such as whether there is scalar data and
> whether it is on points or cells.  In the best of all possible worlds, I
> would want to specify inputs and outputs in a declarative fashion.
> Think of Prolog, with each class's rules specified in XML.  Then you
> could verify the network as it is being built.
> - Drew Dolgert, Cornell Theory Center
>
> > Hi Everyone,
> >
> > I'm wondering what people would think of adding a method
> > GetNumberOfRequiredInputs() to vtkProcessObject.  It would
> > make error checking e.g. in drag-and-drop style visual
> > pipeline building applications easier, since the app would
> > know ahead of time the minimum number of inputs a particular
> > filter requires.
> >
> > Any thoughts?
> >
> >  - David
>
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